See Where Twitter Works

We are inviting a small group of people to become volunteer translators at first. As more folks volunteer, the translation suggestions should accumulate faster and we'll have enough material to respond by making Twitter available not only in English and Japanese but also French, Italian, German, and Spanish. We will distribute the translations to Twitter platform developers, making it easier for them to offer multiple language support as well.

Roughly translated, that means they won't actually be turning the tweets into 140-character foreign language revelations like "Je mange du fromage," but making the services like the site instructions available in more languages using the mass audience of users -- something known as crowdsourcing. That's the same approach that resulted in protocols like @mentions and retweets. International twitterati tech geeks will now be able to help the company's five-person team at the San Francisco headquarters expand the genius tool.